Among known terminal blocks that are attached to a wall of a device box and used for electrical connection between the inside and the outside of the wall is one disclosed in the following Patent document 1. The configuration of this terminal block will be described below briefly with reference to FIGS. 12 and 13. The terminal block 1 is composed of a housing 2, a busbar 3 and a stud bolt 4, O-rings 5 and 6, and a holder 7.
The housing 2, which is attached to a wall of a device box (not shown) by bolts (not shown), has a wall insertion portion 8 to be inserted into an insertion hole that penetrates through the wall and a housing main body 9 which is continuous with the wall insertion portion 8. The busbar 3 has a busbar main body 10, an outside terminal portion 11 which is continuous with the busbar main body 10 at its one end, and an inside terminal portion 12 which is continuous with the busbar main body 10 at its other end. The outside terminal portion 11 is bent from the busbar main body 10 by 90°, whereby the busbar 3 is approximately L-shaped. The terminal block 1 is assembled in such a manner that the busbar main body 10 of the busbar 3 is inserted into the housing 2 and the holder 7.
The busbar 3 is disposed so that the inside terminal portion 12 is exposed inside the wall and the outside terminal portion 11 is exposed outside the wall. In a state that the terminal block 1 is assembled, the stud bolt 4 is inserted in the outside terminal portion 11.
The O-ring 5 serves to ensure necessary waterproofness between the housing 2 and the busbar 3. The O-ring 6 serves to ensure necessary waterproofness between the wall (through-hole) and the housing 2. The holder 7 serves to prevent dropping of the O-ring 5 attached to the housing main body 9. The holder 7 has two lock portions 13, and the housing main body 9 also has two lock portions 14. In the terminal block 1, the holder 7 is fixed to the housing main body 9 when the lock portions 13 are locked on the respective lock portions 14, whereby the O-ring 5 is prevented from coming off.
As seen from FIGS. 12 and 13, the locking between the lock portions 13 and the lock portions 14 is made in the vicinities of portions (bolt fixing holes 15) where the housing 2 is fixed to the wall.
As shown in FIGS. 12 and 13, the busbar 3 is locked on a housing-side lock portion (not shown) which is formed inside the wall insertion portion 8. A busbar-side lock hole 16 is formed in the busbar main body 10. The outside terminal portion 11 of the busbar 3 is formed with a pair of engagement pieces 17.
Referring to FIG. 12, the O-ring 6 is attached to a bottom surface (i.e., a surface opposed to the above-mentioned wall of the device box) of the housing main body 9. The O-ring 6 has an O-ring main body 18 and projections 19 which project from the O-ring main body 18. The projections 19 serve as press-fitting portions for preventing the O-ring 6 from coming off.